Characterization of the Mixing Induced by Multiple Elevated Jets in Cross Flow

2020 ◽  
Vol 399 ◽  
pp. 3-9
Author(s):  
Amina Radhouane ◽  
Nejla Mahjoub Said ◽  
Hatem Mhiri ◽  
Philippe Bournot
Keyword(s):  
Particle Image ◽  
Cross Flow ◽  
Uniform Grid ◽  
Jet In Cross Flow ◽  
Image Velocimetry ◽  
Mass Transfers ◽  
Volume Method ◽  
Heat Transfers ◽  
Injection Ratio

Experimental and numerical consideration is given in the present work to an inline, inclined triple elliptic jet-group discharged in cross flow, a common configuration widely present in several domains, namely environmental, industrial and even medical. The experiments were described by particle image velocimetry and hot wire anemometry measurements, and the numerical simulation was based upon the finite volume method together with a non uniform grid system tightened close to the discharging nozzles. Generally, optimizing similar configurations is meant to reach optimum mixings in terms of heat and/or mass transfers. The present work will be particularly dedicated to the heat transfers generated within the examined multiple jet in cross flow configuration, for jets emitted under an injection height equivalent to , and under a variable injection ratio. After presenting the handled geometry, a validation of the numerical model is proposed. Afterward, a discussion of the reduced static temperature is presented. This is a highly interesting parameter due to its closeness, if not similarity under some circumstances, to the cooling efficiency.

Dispersion of Twin Inclined Fume Jets of Variable Temperature within a Crossflow

2010 ◽  
Vol 297-301 ◽  
pp. 936-941 ◽  
Author(s):  
Amina Radhouane ◽  
Nejla Mahjoub Said ◽  
Hatem Mhiri ◽  
Georges Le Palec ◽  
Philippe Bournot
Keyword(s):  
Temperature Gradient ◽  
Particle Image ◽  
Environmental Concern ◽  
Variable Temperature ◽  
Reynolds Stress Model ◽  
Uniform Grid ◽  
Image Velocimetry ◽  
Turbulent Closure ◽  
Volume Method

This paper deals with the interaction of twin elliptic jets with a cooler oncoming crossflow. The jet nozzles are placed tandem with the main flows, three diameters one from another and initially inclined with a 60° angle. The exploration of the resulting flowfield was carried out numerically by means of the finite volume method together with the RSM (Reynolds Stress Model) second order turbulent closure model and non uniform grid system that was particularly refined near the nozzles. After validation with reference to PIV (particle image velocimetry) experimental data, the model was upgraded by discharging a non reactive fume from the jet nozzles and introducing a variable temperature gradient between the interacting flows. We focused mainly in the present work on the determinant role of the temperature gradient on the dispersion of the discharged pollutants within the domain. Such a study is likely to optimize (control, reduce, eliminate, etc.) one of the most alarming nowadays’ environmental concern: the atmospheric pollution.

Investigation of Combustion Oscillations in a Lean Gas Turbine Model Combustor

2007 ◽  
Author(s):  
Olaf Diers ◽  
Denis Schneider ◽  
Melanie Voges ◽  
Peter Weigand ◽  
Christoph Hassa
Keyword(s):  
Atmospheric Pressure ◽  
Acoustic Pressure ◽  
Particle Image ◽  
Operating Conditions ◽  
Operating Point ◽  
Image Velocimetry ◽  
Different Types ◽  
Mass Flows ◽  
Combined Data

This contribution is a continuation of ASME-GT2006-90300. While still working at atmospheric pressure, the range of operating conditions was extended to more realistic reduced mass flows to reproduce the engine pressure loss and air preheat up to 700K. The thermoacoustic behaviour of the burner was mapped over that operating range. Two different types of oscillations were observed for flames anchored at the nozzle or lifted from it. Both exhibited a frequency dependence on the Strouhal number for constant reduced mass flows. For a selected operating point with the lifted flame at a preheat temperature of 600K and a reduced mass flow of 0.3kg K0.5/(s bar), the thermoacoustic behaviour of the burner was characterised by phase locked Particle Image Velocimetry as well as phase locked OH- and OH-T- LIF measurements and correlated to the acoustic pressure signal obtained by microphones. The combined data showed pulsating combustion being supported through periodic reignition of the main flame zone by a recirculating volume of hot, OH-rich gas, the cycle time being connected to the observed frequency. The characterization of the preheated operating point was completed with a heat balance investigation quantifying the non-adiabatic combustion conditions of the uncooled combustor.

scholarly journals Experimental Study of Heat Convection From Stationary and Oscillating Circular Cylinder in Cross Flow

2000 ◽  
Vol 123 (1) ◽  
pp. 51-62 ◽  
Author(s):  
H. G. Park ◽  
Morteza Gharib
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Particle Image ◽  
Forced Oscillation ◽  
Oscillation Amplitude ◽  
Cross Flow ◽  
Digital Particle Image Velocimetry ◽  
Image Velocimetry ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency

An experimental study is made on the processes of heat transfer from the surface of a forced oscillating cylinder in a crossflow. A range of oscillation amplitude A/D=0.1,0.2, forced oscillation frequency 0<Stc<1, and Reynolds number (Re=550, 1100, 3500) is covered in water Pr=6. Besides the increase at the natural vortex shedding frequency, large increases in the heat transfer are found at certain superharmonics. By using Digital Particle Image Velocimetry/Thermometry (DPIV/T), the increase in the heat transfer rate is found to correlate inversely with the distance at which vortices roll-up behind the cylinder, i.e., the distance decreases when the heat transfer increases. The cause of the increase is found to be the removal of the stagnant and low heat convecting fluid at the base of the cylinder during the roll-up of the vortices.

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